Preheat your oven to 375°F (190°C). This ensures that your breakfast bake cooks evenly and thoroughly.

Grease a large sheet pan (18x13 inches) with cooking spray or olive oil to prevent sticking.

In a mixing bowl, crack the eggs and whisk them together with the milk, salt, black pepper, garlic powder, and onion powder until well combined. This mixture will create a fluffy texture when baked.

Add the crumbled sausage, diced bell peppers, and chopped spinach to the egg mixture. Stir gently with a spatula until everything is evenly distributed.

Pour the egg and vegetable mixture into the prepared sheet pan, spreading it out evenly.

Sprinkle the shredded cheddar cheese evenly over the top. This will melt and create a delicious cheesy layer.

Place the sheet pan in the preheated oven and bake for 25-30 minutes, or until the eggs are set and the top is lightly golden. You can check for doneness by inserting a toothpick in the center; it should come out clean.

Once baked, remove the sheet pan from the oven and let it cool for a few minutes.

Cut into squares and serve warm with optional toppings like sour cream, salsa, or sliced avocado.